Annealing box



Jan. 21, 1947. v

M. L. JACOB 2,414,530

ANNEALING BOX Filed July 26; 1944 INVENTOR AWo/g/ L. J6 cob A i-4mm Patented Jan. 21, 1947 ANNEALING BOX Mory L. Jacob, Pittsburgh, Pa., assignor to Pittsburgh Annealing Box Company, a corporation of Pennsylvania Application July 26, 1944, Serial No. 546,679

3 Claims. 1

This invention relates to annealing boxes and, in particular, to boxes having a hollow stiffening rib extending along their lower edges, adapted to enter the sealing channel formed in the base on which is disposed the charge to be annealed.

Because of the high temperatures to which they are subjected, annealing boxes have a relatively short useful life. After a limited number of heats they are apt to become warped or otherwise deformed to such an extent that they cannot be used any further. Another difficulty experienced with annealing boxes of the types known previously is that the charge being annealed, i. e., a stack of sheets or a group of coils of strip, is not heated to precisely the same temperature at all points throughout its mass.

I have invented a novel form of annealing box having a useful life greater than that of boxes known previously and capable of producing more uniformly annealed material than has been obtainable with boxes of known construction. In a preferred embodiment, I provide an annealing box having a hollow duct or passage along the lower edges of its sides and ends with means for causing a flow of gases therethrough. Specifically, I provide inlet and outlet holes in the duct and a chimney or flue extending upwardly from the outlet holes whereby to induce a flow of gases through the duct by natural draft. The holes may conveniently be formed at the corners of the box and I prefer to utilize the holes at two diagonally opposite corners as inlets and the remaining holes as outlets. The inlet holes may be provided with short chimneys but the chimneys on the outlet holes are several times as high as the chimneys from the inlet holes to provide sufiicient differential in gas pressure to secure a good draft through the duct.

Further details, novel features and advantages of my invention will become apparent during the following complete description and explanation which refer to the accompanying drawing illustrating the preferred embodiment. In the draws,

Figure 1 is a plan view;

Figure 2 is a side elevation partially broken away showing a portion of one end wall and the top of the box and section;

Figure 3 is an end elevation;

Figures 4, 5 and 6 are partial sectional views to enlarged scale, taken along the planes of lines IVIV, V-V, VI-VI of Figure 2, respectively.

Referring in detail to the drawing, the annealing box of my invention indicated generally at H] is preferably fabricated from metal plate by welding although it may constitute a casting. The box H] has sidewalls H, end walls l2. and a top I3. It is open at the bottom so it may be placed over the charge to be annealed when the latter has been disposed on the usual supporting base (not shown). A duct or passage I4 extends continuously around the lower edges of the side and end walls. As shown in Figures 4 through 6, the passage is V-shaped in section, terminatin in a, bottom edge adapted to penetrate sealing material such as sand with which the sealing channel formed in the charge-supporting base is usually filled. The duct 14 is formed by flange plates [5 normal tothe side and end walls, and inner and outer sideplates l6 and [1. These plates are all welded together to form a con tinuous gas-tight duct extending around the four sides of the box at the bottom thereof.

The sidewalls II have adjacent panels It la and Hb in staggered relation, the panels Ha being substantially coplanar with the plates I6 and the panels Hb lying in the vertical plane through the outer edges of plates l5 and I1. The end walls l2 and the top I 3 are of similar construction. The staggered or offset panels of each wall and the top may conveniently be formed by bending a single plate, adjacent panels being connected by webs I 8 at right angles thereto. The upper panels |3a of the top are beveled adjacent their ends as at Hi. It will be evident that the construction of the side and end walls and the top is such as to give them great rigidity.

The side and end walls II and I2 rest on the plate l5 of the duct l4 and are welded thereto. Holes 20 are formed in the plate l5 at points spaced along the length of the duct l4 and prefferably adjacent each corner of the box. As shown in Figure 1, the holes 20 extend around the corners and on both sides thereof. Certain of the holes 20, e. g., two diagonally opposite holes, are provided with chimneys 2! extending upwardly therefrom to a height of about one-third that of the box W. The chimneys are preferably composed of angle plates having flanges 2 la abutting the side and end walls of the box. The chimneys 2| cause a circulation of gases through the duct 14 by natural draft, the gases entering the holes 20, passing through the duct 14 along the sides and ends of the box and thence upwardly through the chimneys. If desired, the inlet holes 20 may be provided with short chimneys 22 preferably having a height of not more than one-third that of the chimneys 2|. This insures a suflicient differential between the pressures at the top of the 3 chimneys 2| and 22 to maintain a good draft through the duct I 4.

The circulation of gases through the duct M serves two purposes. In the first place, it maintains the temperature of the lower edges of the box substantially uniform through the length and breadth thereof and thus reduces the amount of distortion as by warping, resulting from the successive heating and cooling stages of the annealing cycle. The circulation of gases materially reduces the tendency of the walls of the box to buckle, collapse or be otherwise deformed. Secondly, the circulation of gases through the duct tends to minimize any differences between. the. temperature of the charge within the box, at different points therein. As a result, the annealed product is more nearly uniform in physical characteristics throughout the mass of the charge.

It will be apparent from the foregoing that the annealing box of my invention is characterizedby important advantages over such boxes as constructed heretofore, with particular reference to their useful life and the uniformity of treatment of the annealed material. The provisions disclosed for maintaining a circulation of gases through the duct along the bottom edge of the side and end walls of the box. do not materially increase: the overall cost of the box. The functioning of the chimneys requires no attention from the operators of the annealing furnace, their action being entirely automatic in accordance with well-known physical laws. The chimneys perform their function on both the heating 4 and cooling stages of the annealing cycle. During the heating stage, the chimneys cause the circulation of furnace gases through the duct,

thereby supplying heat adjacent the bottom of the charge. During the cooling stage, after the bases with the boxes thereon have been removed from the furnace, the chimneys cause a circulation of" air through the duct thereby expediting the cooling.

Although I have illustrated and described but a preferred embodiment of my invention it will be recognized that changes in details of construction may be made without departing from the spirit of the invention or the scope of the appended claims.

I claim:

1. In an annealing box, side walls, end walls and. a top, the.- box being open at the bottom, a duct extending along the lower edges of said walls, said duct being defined by walls which are continuous and uninterrupted on all sides throughout substantially their entire length, inlet and outlet holes in said duct spaced apart therealong, and a chimney extending upwardly from the outlet hole adapted to produce a natural draft longitudinally through the duct.

2. The apparatus defined by claim 1 characteriZed by said holes being located adjacent the corners of the" box.

3. An annealing box asdefined by claim 1 characterized by said duct being V-shaped in. section and terminating in a bottom edge adapted to penetrate a bed of granular. sealing material.

MORY L. JACOB. 

